Cincinnati-area homeowners are realizing the biggest sales gains in more than 15 years, raking in an average $21,000 above purchase price in the third quarter this year, according to housing tracker, ATTOM Data Solutions.

The average sales gain was the highest recorded in Greater Cincinnati since ATTOM, formerly RealtyTrac, began tracking sales prices in 2000.

It's also more than enough to cover the traditional 20 percent down payment on a 30-year, fixed-rate mortgage for a home that costs $198,657 – the Cincinnati-area’s average home price in September, according to the Cincinnati Area Board of Realtors (CABR).

“There are more homeowners now in Cincinnati who actually have enough equity to sell and walk away with enough money to put down on a new home,’’ said Daren Blomquist, senior vice president at ATTOM. "The challenge becomes finding a new home to buy and being able to afford that.’’

That’s still a tougher challenge in Cincinnati than most other parts of the country.

About 11.4 percent of Cincinnati-area homeowners are seriously underwater, or owe at least 25 percent more on their mortgages than their homes are worth, according to Blomquist. That compares to a national average of 9.5 percent of homeowners who are seriously underwater, he said.

Such negative equity would eat into any sales gain and still leave the homeowner unable to afford to move.

In addition, the number of available homes for sale continues to decline, plummeting nearly 13 percent from the same month a year ago to 5,633, according to the CABR report.

“It’s the same story; just a different month. Our inventory numbers remain low due to the continued, quick turnover of property. The market is strong and property that is in “move-in” ready condition in a desired location is selling quickly, sometimes with multiple offers,’’ said CABR President David Welch.